The invention discloses a multi-stage depressed collector material and preparation and a surface treatment method thereof, which relates to a vacuum electronic technology and is a novel microporous electrode material which can be used for a multi-stage depressed collector of a satellite traveling-wave tube and a treatment process thereof. The electrode material has a micron/submicron-level microporous structure and is beneficial to inhibiting secondary electron emission and improving the recovery efficiency of the multi-stage depressed collector, thereby improving the overall efficiency of the traveling-wave tube. The method has the advantages of simple and controllable process and low cost. Compared with the surface modified by ion beams, the electrode surface of the prepared multi-stagedepressed collector has the same effect on inhibiting secondary electron emission.